Preventing Ice Dams on your Roof

Get tips on preventing ice dams from forming on your home's roof this winter. Learn how using Ice & Water Shield under your roof shingles can prevent ice dams and leaks.

LESLIE: Monique is calling in from New Hampshire. She’s got a question about flooring[1]. What can we do for you?

MONIQUE: Actually, this winter[2] was a rough winter for New Hampshire and I had ice dams[3] on my roof outside …

TOM: Oh, that’s nice.

MONIQUE: … which caused a leak that came into the house through the door frame – which was under a covered porch – and it buckled my hardwood floor.

TOM: Oh, too bad.

MONIQUE: So, my question is – I’ve had lots of advice as to how to prevent the ice dam next year. I’ve got insurance fixing the floor for me but I’ve got to take care of the bigger issue, which is how to prevent this from happening again.

TOM: Well, first of all, your roof in New Hampshire, I would have thought that it was constructed with something called Ice & Water Shield[4], which would have prevented this. It sounds like it wasn’t.

The first thing that you should do – and this should be covered by the insurance company as well, I would think – is you need to remove the roof shingles along the first three to four feet of the roof and apply something called Ice & Water Shield. You might want to go to the website for Grace Construction Products Company; it’s GraceAtHome.com[5]. They pretty much invented this product, Ice & Water Shield. And it’s sort of a rubbery, three-foot-wide sheet that’s put right against the roof sheathing all along that edge and what it does is if you get any ice that backs up at the roof edge, it can’t get under the shingles and leak through to the house.

MONIQUE: OK.

TOM: It can get under there but it’s not going to leak and that’s why you put in Ice & Water Shield. And in your part of the country, Ice & Water Shield should be a standard part of any roofing project. I’m surprised you don’t have it.

Now beyond that, it’s a good idea to have proper ventilation[6]; which means the overhang, if there are soffits there, have to be open and free flowing and the insulation should not block those soffits. In other words, you should make sure that the insulation in the attic doesn’t push so far forward towards the exterior wall that it blocks the air flow. You have Ice & Water Shield …

LESLIE: Mm-hmm. Sometimes, there’s even plywood blocking the soffits.

TOM: Well, I mean that assumes that she has vents.

LESLIE: Right.

TOM: I mean you do need to make sure you have vents. But if you have good ventilation and you have Ice & Water Shield, you shouldn’t really have an ice-damming problem next year.

MONIQUE: That is good. Thank you very much.

TOM: You’re welcome, Monique. Thanks so much for calling us at 1-888-MONEY-PIT.